1. Field of the Invention
The present invention relates to a battery pack usable as a power source of an electric device, and a battery pack system configured to include therein the battery pack and the electric device, and more particularly to such a battery pack and such a battery pack system each of which includes therein a battery cell group of a plurality of serially-interconnected battery cells or a serial array of battery cells, wherein each battery cell is in the form of a rechargeable battery such as a Li-ion battery.
2. Description of the Related Art
An electric device is primarily powered by an AC voltage supplied from a commercial power source, or a DC voltage supplied from battery cells. As one of performance characteristics required for an electric device, a high output is focused on. To drive the high-output electric device with energy stored in a battery pack, the battery pack is required to output a high voltage. An example of such a conventional battery pack or such a battery pack system is disclosed in Japanese Patent Nos. 4104648 and 4216898.